Generally, an imaging apparatus such as color television or a video cassette recorder may include a built-in device for receiving teletext or other relevant information thereat. This allows persons either from home of from the office, to receive newly changed data information. In today's fast moving information age, if the desired information is selected, the full page containing the desired information is again displayed. In other words, the conventional apparatus for receiving teletext requires that the pages containing the desired information must be fully reproduced on a corresponding display, irrespective of the amount of data which has actually been changed. It will be noted that the transmitting end of the teletext system transmits the latest information but only selected portions of this information are changed and then only on an irregularly occurring basis. On the other hand, at the receiving end, all of the pages, i.e., complete pages containing both the changed and the unchanged portions of the information, are being displayed.
It will be appreciated from this discussion that there is a problem in the conventional apparatus in that the desired latest information is not easily watched, i.e., distinguished, because the previous information corresponding to unchanged information must be watched again.
U.S. Pat. No. 4,991,017, which is entitled "RECEIVER FOR TELEVISION AND TELETEXT SIGNALS, INCLUDING DECODER AND AN ADAPTIVE WAITING TIME REDUCTION CIRCUIT", discloses an apparatus for storing desired teletext page numbers in a page number memory and for retrieving teletext for the corresponding page numbers by a searching operation. The order of priority of these pages can be allocated to a page number of the memory, thereby reducing the waiting time. According to this patent, if the memory becomes full, the oldest requested page number is erased from the memory, thereby maintaining the latest page numbers active.
However, even in an apparatus constructed according to the above mentioned patent, when the user wants to receive information, the whole information corresponding to the stored page numbers must be displayed. Consequently, the user is unable to readily distinguish between old and new teletext information.